j1

[James Bowman] of the Willow Garage published a paper on his J1 CPU core for field-programmable gate arrays. This was originally developed and used for the Ethernet cameras on the PR2 (you know, that incredibly expensive beer delivery system?) robot. It uses a 16-bit von Neumann architecture and lacks several processor features you’d expect a CPU to have such as interrupts, multiply and divide, a condition register, and a carry flag. None-the-less, its compact at just 200 lines of Verilog and it can run at 80 MHz. [James] compares the J1 to three different FPGA CPU Cores commonly used and discusses how the system is built in his 4-page paper that has the details you’re interested in but won’t take all day to dig through.